This invention relates to an electro-therapy method and apparatus and more particularly to a method and apparatus for relieving pain arising from temporary or chronic conditions or during or after surgery.
Nemec in U.S. Pat. No. 2,622,601 issued on Dec. 23, 1952 disclosed one of the earliest electro therapy apparatuses and method. The Nemec system disclosed an apparatus comprising at least two means for producing alternating currents of frequencies between 1000 and 10,000 cycles with each of means connected with a separate pair of electrodes. The difference frequency between the means was made less than 100 cycles. The electrodes were placed upon the patient such that the two currents would intersect at a proposed therapeutic site. The basic concept was that the higher frequencies would be transmitted, but the low frequency need for therapeutic action would occur only at the common transmission point.
Nemec in U.S. Pat. No. 4,023,574 issued May 17, 1977 disclosed three separate pairs of electrodes are attached to a body part to be treated, spaced apart around said part of the body. A primary alternating electrical current having a primary frequency of between 100 Hz and 100,000 Hz is passed between one of the electrode pairs. A similar second alternating electrical current having a secondary frequency in the same range as the primary frequency but differing by between 50 Hz and 100 Hz from the primary frequency is passed between another of the pairs of electrodes. A tertiary alternating current is passed between the third pair of electrodes and has a tertiary frequency differing by at most 1 Hz from the frequency of either the primary current, the secondary current, or the arithmetic means of the frequency of these two currents.
Hunsjurgens' U.S. Pat. No. 3,774,620 issued on Nov. 27, 1973 disclosed an electro-medicinal apparatus for use in interference current therapy. The apparatus has at least two circuits that act on the patient through electrodes, the currents producing s stimulus active interference on a target area on the patient by superimposing the two or more currents, which by themselves have no stimulating effect, the currents differing from each other by a low frequency value. A particular feature of the apparatus is that the circuits produce an optimum interference at the treatment area and include a current strength-regulating member, which can operate during treatment.
Rodler disclosed in U.S. Pat. No. 3,958,577 issued on May 25, 1976 an apparatus for producing interference and beat-currents in a selectable point of the body, particularly for electrotherapy on the human body, which comprises at least two pairs of electrodes adapted to be applied to the human body. Each of the pairs of electrodes has associated therewith an output amplifier. The latter supplies independently selectively pulse and alternating current for each pair of the electrodes. A voltage proportional in amplitude to the current flowing through the patient is taken. The voltage relates mathematically each individual setting voltage with a common setting and is subtracted. The difference voltage is produced separately for each circuit and used for the amplification control on the corresponding of the amplifiers, and the voltage is so polarized that an increase in patient current resulting in a decrease of the amplification and an increase in the joint voltage resulting in an increase of the amplification.
Nawracaj et al. disclosed in their U.S. Pat. No. 4,071,033 issued on Jan. 31, 1978 that a master oscillator, whose output is split and applied to two frequency dividers that divide the frequency by different numbers, initiates stimuli. The two frequencies thus derived are applied to wave shapers to provide a desired waveform such as a half sine wave, and also each signal is further divided by a common number. The two signals are then amplified, and applied to the body through a probe whose contacts are arranged so that the two stimuli currents are orthogonal to each other. The two high frequency signals heterodyne within the human muscle to produce a single low frequency stimuli, useful for the production of muscle contraction, hyperemia, electro analgesia and muscle relaxation.
Masaki disclosed in U.S. Pat. No. 4,960,124 issued on Oct. 2, 1990 a apparatus for low-frequency electrotherapy wherein the output current of a low-frequency oscillator is applied to the subject's body through a pair of electrodes placed on the subject's body, comprising a first oscillator circuit that generates a low-frequency square wave voltage when the load is in connection with the electrode pair; and a second oscillator circuit that generates a therapeutic voltage when the output voltage of the first oscillator circuit is not zero.
Matthews' U.S. Pat. No. 5,269,304 issued on Dec. 14, 1993 discloses an electro-therapy apparatus that includes at least two electrodes adapted to feed oscillating current to selected sites on or beneath the epidermal or mucous surface remote from a treatment site. A common return electrode is provided at the treatment site that is subjected to the sum of the currents from the two feed electrodes. The feed electrodes may be contact feed electrodes or capacitive feed electrodes. The feed electrodes may operate at different frequencies so that the treatment site is stimulated by the beat frequency. This may be at or about 80 or 130 Hz, if an anaesthetizing effect is required.
Reiss' U.S. Pat. No. 5,324,317 issued on Jun. 28, 1994 discloses an interferential stimulator for applying two medium frequency alternating currents of slightly differing frequencies to the body of a living being so that they cross and interact to produce a low frequency therapeutic current at a selected point. A fixed frequency is generated and applied to the skin through a first electrode pair. A second frequency, differing from the first by from about 1 to 150 Hz is applied through a second electrode pair. The electrodes are arranged to deliver a localized stimulation. At the crossing point of the four electrodes, the heterodyne process for specific point stimulation produces a low frequency beat or pulse. The stimulator may be operated in any of several modes. First, constant stimulation may be applied at fixed frequency difference between electrodes. Second, the frequency difference can be decreased abruptly and returned to the original frequency difference over about 1 second. Third, the frequency difference can be decreased abruptly about 50% and returned over a typically 8 second period. Fourth, a gradual about 50% drop in frequency difference may be accomplished gradually and returned over typically a 10 second period. This device has been found to be useful in reducing pain, and appears to provide benefits in reducing edema and inflammation, increasing blood flow and reducing muscle spasms.
Each of the above devices or methods has one or more undesirable effects or deficiencies that the disclosed invention solves.